Ultraweak fiber bragg grating array and Phi-OTDR combined optical fiber vibration sensing system

A fiber grating array and weak fiber grating technology, applied in the direction of measuring ultrasonic/sonic/infrasonic waves, measuring devices, instruments, etc., can solve the problems of low detection range and sensitivity, and achieve the effect of improving signal-to-noise ratio and sensitivity

Inactive Publication Date: 2015-12-23
UNIV OF ELECTRONIC SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the ordinary Φ-OTDR system, the detection range and sensitivity are re

Method used

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  • Ultraweak fiber bragg grating array and Phi-OTDR combined optical fiber vibration sensing system
  • Ultraweak fiber bragg grating array and Phi-OTDR combined optical fiber vibration sensing system
  • Ultraweak fiber bragg grating array and Phi-OTDR combined optical fiber vibration sensing system

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Effect test

Embodiment 1

[0039] An optical fiber vibration sensing system combining an ultra-weak fiber grating array and a Φ-OTDR, in which an ultra-weak fiber grating array is connected to the sensing fiber part of the optical fiber vibration sensing system. The spacing of the ultra-weak fiber grating array is the same as the spatial resolution of the system or an integer multiple of the spatial resolution. The signal returned in the sensing fiber is the superposition of the reflection signal of the ultra-weak fiber grating and the back Rayleigh scattering signal.

Embodiment 2

[0041] An optical fiber vibration sensing system combining an ultra-weak fiber grating array and a Φ-OTDR, in which an ultra-weak fiber grating array is connected to the sensing fiber part of the optical fiber vibration sensing system. Each ultra-weak fiber grating should be arranged at equal intervals in the sensing fiber. The spacing of the ultra-weak fiber grating array is the same as the spatial resolution of the system or an integer multiple of the spatial resolution. The signal returned in the sensing fiber is the superposition of the reflection signal of the ultra-weak fiber grating and the back Rayleigh scattering signal.

Embodiment 3

[0043] An optical fiber vibration sensing system combining ultra-weak fiber grating array and Φ-OTDR, the sensing fiber adopts ultra-weak fiber grating array. The spacing of the ultra-weak fiber grating array is the same as the spatial resolution of the system or an integer multiple of the spatial resolution. The signal returned in the sensing fiber is the superposition of the reflection signal of the ultra-weak fiber grating and the back Rayleigh scattering signal.

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Abstract

The present invention discloses an ultraweak fiber bragg grating array and Phi-OTDR combined optical fiber vibration sensing system. According to the system, the ultraweak fiber bragg grating arrays are accessed in a sensing optical fiber with the same spacing, and the spacing selection must be same with the spatial resolution of a Phi-OTDR optical fiber sensing system or must be integer multiples of the spatial resolution. By utilizing the reflection characteristics of the ultraweak fiber bragg gratings, the optical power of the detected backward rayleigh scattered light is improved, thereby improving the signal to noise ratio and the sensitivity of the Phi-OTDR optical fiber vibration sensing system.

Description

technical field [0001] The invention relates to the technical field of optical fiber vibration sensing system based on Φ-OTDR, mainly improving the structure of sensing optical fiber, and specifically relates to an optical fiber vibration sensing system combining an ultra-weak fiber grating array and Φ-OTDR. Background technique [0002] In the Φ-OTDR optical fiber vibration sensing system, the continuous light wave emitted by the narrow linewidth laser is injected into the sensing fiber through the circulator after pulse modulation and optical amplification. The light injected into the fiber in Φ-OTDR is strongly coherent, so the output of the system is the result of the interference of backscattered Rayleigh light within the pulse width range. Assuming that the sensing fiber is in an ideal state, the back Rayleigh scattering waveform returned through the sensing fiber should be constant, if a perturbation is added to a certain point in the sensing fiber, then the sensing f...

Claims

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Application Information

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IPC IPC(8): G01H9/00
Inventor 岳慧敏熊竹魏豪李剑峰张博
Owner UNIV OF ELECTRONIC SCI & TECH OF CHINA
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